Channel Characterization for Free-Space Optical Communications.

摘要

The current DARPA Free space Optical Experimental Network Experiment (FOENEX) Program is a continuation of the earlier Optical RF Communications Adjunct (ORCA) Program that was designed to bring high data rate networking to the warfighter via airborne platforms. The FOENEX program is headed by the Applied Physics Laboratory (APL) of the Johns Hopkins University. Radio frequency (RF) equipment and networking was designed and built by L3 and the adaptive optics (AO) subsystem was designed and built by AOptix. Phase 0 testing of the FOENEX hybrid system took place during June 2011 at Hollister Air Force Range in California and Phase 2 Final Testing was performed in March and April of 2012 at the Naval Air Weapons Test Range in China Lake, California. The University of Central Florida (UCF) was separately contracted by DARPA to measure path-averaged values of the refractive-index structure parameter 2 C(exp 2)(sub n) , the inner scale of turbulence l0, and the outer scale of turbulence L0 along the propagation path from a Twin Otter aircraft to a ground site (G6) at China Lake, CA. The nominal range to the aircraft from the ground site at G6 was 50 km, but variations in range extended from 30 km to 75 km. Although not part of the original Statement of Work (SoW), UCF also provided the same measurements at Hollister Air Force Range between the Hollister Airport and Fremont Peak over a path length of 17 km. In addition, UCF researchers also provided a comparison of theoretical models with measured quantities from the optical data beam during testing at both sites to ascertain some assessment of system performance. The UCF team took direct measurements of only the beacon beam at Hollister and China Lake which led to path-averaged values for the atmospheric parameters.